Synchronizing apparatus



Jan. 8, 1957. J, D. MOYNIHAN 2,777,075

SYNCHRONIZING APPARATUS Flled March 24, 1954 WLIHI" 5 Ill 0 N U aoi United States Patent SYNCHRONIZING APPARATUS John D. Moynihan, Verona, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., 2 corporation of Pennsylvania Application March 24, 1954, Serial No. 418,420

11 Claims. (Cl. 307-87) My invention relates, generally, to synchronizing apparatus, and it has reference, in particular, to automatic synchronizing apparatus for controlling a circuit breaker to effect a connection between alternating-current circuits connected to different sources.

A need exists for a simple and effective automatic synchronizer which is readily adaptable for frequencies of from 25 to 1600 cycles per second or more with a minimum of change. Such change would involve only the changing of a small number of resistor-capacitor networks, which could be of a plug-in type, facilitating not only adaption to different frequencies, but also the sensitivity to the frequency difference of the circuits to be synchronized, so that the synchronizer can be set to close at any phase relationship, as well as when the difference frequency is less than any prescribed amount, down to about one cycle in six seconds. This difference can be decreased by increasing the elements of the counting chain utilized.

It is, therefore, an object of my invention to provide a simple, readily adaptable synchronizer and for automatically synchronizing two alternating-current circuits over a wide range of frequencies.

One object of my invention is to provide for counting a predetermined number of successive coincident cycles of two alternating-current sources before closing a circuit breaker to connect them.

Another object of my invention is to provide for using a counting circuit to count successive coincident cycles of two alternating-current circuits and for closing a circuit breaker connecting the circuits, only if a predetermined number of successive cycles of the source frequencies are coincident, and for resetting the counting circuit in the event that they are not.

Yet another object of my invention is to provide in automatic synchronizing apparatus for counting successive coincident cycles of two alternating-current circuits, and stopping the counting operation in the event that there is a break in the chain of successive coincident cycles.

It is an important object of my invention to provide for automatically connecting two alternating-current circuits, only when they have remained substantially in phase for a predetermined number of successive cycles.

Other objects will, in part, be obvious, and will, in part, be explained hereinafter.

In accordance with one embodiment of my invention, voltages from two alternating-current circuits which are to be connected when they are in synchronism, are separately applied to clipping and differentiating circiuts, so as to produce relatively short voltage pulses or pips in each positive half cycle. These pulses are applied to a gate valve device for rendering it conductive only when the pulses from the two circuits are substantially coincident. The gate valve applies voltage pulses to a counting chain of valve devices which are rendered conductive: in sequence, the last one operating a relay to close a circuit breaker for connecting the circuits. Blocking 2,777,075 Patented Jan. 8, 1957 pulses are applied to'the odd and even numbered valves alternately, from a pulse divider which is triggered by an auxiliary gate valve controlled by the main gate through a phase shift circuit, so that the last operative valve of the counting circuit will be reset in the event that coincidence of pulses is lost at anytime before the completion of a counting operation.

For a more complete understanding of the nature and scope of my invention, reference may be made to the following detailed description, which may be read in connection with the accompanying drawing, in which the single figure is a diagrammatic view of synchronizing apparatus embodying the invention in one of its forms.

Referring to the drawing, the reference numeral 10 may denote a circuit breaker for connecting alternatingcurrent circuits represented by the conductors 13 and 14, which may be energized from different sources. The circuit breaker 10 may be provided with an operating winding 15, and may be latched in the closed position by means of a latch 17 and an associated trip device 18 for releasing it. A closing relay 20 having an operating winding 21 may be provided for connecting the operating winding 15 of the circuit breaker to a suitable source of electrical energy for closing the breaker.

In order to provide for closing the circuit breaker 10, only when the circuits 13 and 14 are substantially in synchronism, operation of the closing relay 20 may be controlled by a counting circuit 22 responsive to pulses of electrical energy, comprising a plurality of valve devices, there being ten such devices, for example, identified as devices T1, T2, etc. through T10. The valve devices T1 through T10 may be arranged in cascade relation, so that as each one is rendered conductive by a pulse, the preceding valve device in the chain is rendered nonconductive, and the succeeding valve device is conditioned to render it conductive in response to the next pulse of electrical energy.

For example, a set-up circuit comprising a valve device T12 may be provided, which is connected in cascade with the valve devices T1 through T10 so that the control electrode Tle of valve T1 is connected to the cathode circuit of valve T12, to thereby be biased positive by virtue of the drop across cathode resistor 25 when valve T12 is rendered conductive upon the application of power to the anode T1212 thereof. The control electrode T22 of valve T2 is likewise connected to a cathode resistor 26 in the cathode circuit of the valve T1. The control electrodes of the valve devices T3 through T10 are similarly connected, so that each valve has its control electrode rendered more positive when the previous valve is rendered conductive.

The anodes of the valve devices T12 and T1 through T10 may be connected by capacitors 28. These capacitors may be connected to the anodes on the anode side of anode resistors 29, which are connected in series with the anodes of the valve devices and the source of anode potential. By thus connecting the anodes, as each successive valve device is rendered conductive, the anode potential of the previous valve device will be further dropped by the amount of the voltage across the capacitor 28, thereby rendering the previous valve device nonconductive. By this arrangement, the valve devices T1 through T10 will be rendered conductive in sequence in response to successive pulses to perform a counting operation for controlling the closing relay 20, which may be connected in the cathode circuit of the valve device T10, so as to be operated when the valve device T10 becomes conductive.

Operation of the counting circuit 22 may be controlled by a gate circuit comprising a valve device T14. The control electrodes of the valve devices T1 through T10 may be connected through blocking capacitors 30 to the cathode side of a cathode resistor 32 in the circuit of the valve device T14, so that each time the valve device is rendered conductive, a positive voltage pulse is applied to the control electrodes.

Operation of the valve device T14 may be controlled by applying control voltage pulses to the control electrode T14-e thereof from the circuits 13 and 14-. The pulses from circuit 14- may be obtained by applying the voltage from a potential transformer 34, connected to the conductors of circuit 14, to a clipping circuit 35 comprising inversely disposed valve devices T15 and The valve device T15 is so connected in circuit with the secondary of the transformer 34, and a resistor 37, with its anode T15a grounded and its cathode T150 connected to the resistor, that substantially no voltage appears on negative half cycles. The valve device T16 is connected in the opposite sense, with a bias voltage applied to the cathode T160 from a voltage divider resistor 39, so that the valve device will not conduct until a relatively high value of voltage is applied, whereupon the output voltage appears across the resistor 411 in a substantially square wave form. This voltage is applied to a differentiating circuit 42, which may be of a plug-in type so as to be readily changeable, comprising a capacitor 43 and resistor 4-4, so that the resultant wave form is in the form of a pip or pulse with a leading edge shaped similar to the leading edge of the square wave and an exponential trailing edge governed by the time constant of the differentiating circuit. The width of the pip may be varied by changing the values of resistor 44) and capacitor 43 according to the formula where t is the duration in seconds of the pip, and er and e2 are the voltages across resistors 40 and 44, respectively. This pip is applied to the control electrode T14e of the valve device T14, but in itself is insufficient to render the valve device conductive, because of a negative bias applied to the control electrode thereof from voltage divider 45.

In order to render the valve device T14 conductive, only when the voltages of the circuits 13 and 14 are substantially in phase, a potential transformer 47 may be used to derive a voltage from the circuit 13, which may be applied to a clipping circuit 35 and a differentiating circuit 42, so as to produce a pulse of greater magnitude and longer duration than the control pulse, the duration being accomplished by selecting appropriate values of R and C according to the formula above. It may then be applied to still another clipping circuit 35 before being applied to the control electrode T14e of the valve device T14 to give an essentially square wave gate signal of slightly greater duration than the control pulse to allow some latitude in phase relation for synchronizing. When the pips from both circuits are substantially in phase, their cumulative effect will be sufficient to overcome the bias from the voltage divider 45, and renderthe valve device T14 conductive. Thus, voltage pulses will be applied to the counting circuit 22 from the cathode resistor 32 each time the voltages of the circuits 13 and 14 are within the desired phase relation.

In order to require a predetermined number of consecutive cycles of the circuits 13 and 14 to be in phase before the circuit breaker is closed, blocking means 50 may be provided for applying blocking pulses and resetting the counting circuit 22 in the event that at least a predetermined number, for instance 1d consecutive cycles, are not in phase. The blocking means 513 may comprise a pulse dividing circuit 52 including valve devices T17 and T18 which are alternately rendered conductive. The valve device T17 may have its control electrode T17e connected to a source of more positive bias through a resistor 54 so as to be rendered conductive on the first pulse applied to the control electrodes of the two valve devices. The control electrode T18e of valve device T18 may be connected to the cathode side of a cathode resistor 55 in the circuit of the valve device T17 so as to be biased sufiiciently positive upon the valve device T17 being rendered conductive to be itself rendered conductive on the next impulse. A capacitor 56 prevents the bias on T1 18 from changing during the application of the first pulse sufliciently for this pulse to render T18 conductive. The anodes of the valve devices T17 and T18 may be connected by a blocking capacitor 28 which operates in a manner previously described in connection with the valve devices T1 through T10, so that when valve device T18 is rendered conductive, it reduces the anode voltage of the valve device T17 and renders it nonconduc'tive. In this manner, valve devices T 17 and T18 will be alternately rendered conductive and will apply voltage pulses to the cathodes of the even numbered and odd numbered valve devices, respectively, of the counting circuit, to render these valve devices nonconductive.

Operation of the pulse dividing circuit 52 may be controlled by an auxiliary gate circuit comprising a valve device T19 to which voltage pulses are applied from the potential transformer 47. The anode T 19a is also connected to a source of positive voltage through a resistor 57 for providing continued conduction until a reset pulse is applied. The control electrode T19e may be connected to the cathode resistor 32 of the main gate valve device T1 1 so that the valve device T19 is initially rendered conductive only when the voltage pulses from the circuits 13 and 1d are sufiiciently coincident that they overlap at least in part. The output voltage from the cathode circuit of the auxiliary gate device T19 is applied from the cathode resistor 59 through a blocking capacitor 60 and a phase shift circuit 61 comprising a resistor 62 and capacitor 63, to a clipping circuit 35 and a differentiating circuit 42 and thence to the control electrodes of the valve devices T17 and T18 through coupling capacitors 64 and d5, causing the valve devices T17 and T18 to conduct on alternate pulses, thus applying blocking pulses from the cathode resistors 66 and 67 to the cathodes of the even and odd numbered counting devices, respectively.

In order to provide for resetting the circuit, the cathode T19c of the auxiliary gate valve may be connected to the anode side of a resistor 68 in the anode circuit of the valve devices T1 through T10 through a capacitor 69 so that a reset voltage pulse may be applied to the cathode of the auxiliary gate device to render it nonconductive whenever the voltage drop through the resistor 68 is reduced by reason of the valve devices T1 through T11) being rendered nonconductive as at the end of a partial counting operation. This results in a sud-den change in voltage, producing a reset pulse which is also applied to the valve device T18 through capacitor 71 to render it conductive, so that valve device T17 will be conditioned to conduct on the next pulse.

When power is applied to the valve device T12 initially, this valve device becomes conductive, since a pulse is applied to the control electrode T12e from resistor 68, and it applies a positive bias to the control electrode Tle due to the voltage drop across the cathode resistor 25. As soon as the voltage pulses applied to the main gate circuit valve device T14 from the circuits 13 and 14 are coincident, the valve device T14 will be rendered conductive, and the voltage pulses across the cathode resistor 32 will be applied to the control electrodes of the. valve devices T1 through T10. Because of the bias. from the cathode resistor 25, valve device T1 will be rendered conductive with the first pulse. This conditions valve device T2, since the voltage bias from the cathode resistor 26 is now applied to its control. electrode. T2e. Upon. the second coincident pulse, the valve device T2 will be rendered conductive. As soon as this valve device is rendered conductive, the anode Tla will be reduced in voltage by the amounts of the voltages across the capacitor 28 and the anode resistor 29 of valve device T2, reducing the anode voltage and thus rendering the valve device T1 nonconductive. The valve devices T3 through T will thus be successively rendered conductive and nonconductive, and upon valve device T10 becoming conductive, closing relay 26* operates, connecting the operating winding of the circuit breaker 10 to the control source, so that the circuit breaker closes and connects the circuits 13 and 14, only after a predetermined number of cycles of the source frequencies have been in phase.

In a normal counting operation, each of the valve devices of the counting circuit is rendered nonconductive upon the next valve device becoming conductive. In the event that a limited number of cycles of the source frequencies should be in phase, so that a counting operation might have proceeded part way, with a subsequent failure of concidence, the blocking means 50 serves to render the last conductive valve device of the counting chain nonconductive. Each time the main gate circuit valve device T14 applied a pulse to the counting circuit 22 it also applies a similar pulse to the control electrode T19e of the auxiliary gate valve device through conductor 70. The first one of these renders the auxiliary gate valve device T19 conductive until a reset pulse is applied, and a voltage pulse is thereupon applied through the phase shaft circuit 61, clipping circuit 35' and differentiating circuit 42. to the impulse divider 52, causing valve device T17 to conduct and apply a pulse from cathode resistor 66 to cathode T 2c. This impulse is delayed with respect to the impulse from the main gate circuit by reason of the phase shift circuit 61, and permits a conducting valve device to conduct for a sufficient time to insure blocking the previous valve device. Alternate pulses are applied by the valve devices T17 and T18 to the even and odd numbered valves of the counting chain. Thus, in the event that one of the valve devices should fail to fire because of a failure in coincidence of the pulses from the circuits 13 and 14-, the preceding valve device, for example T1, would remain conductive. However, the next delayed impulse from the impulse divider circuit 52 is effective to render such preceding valve device T1 nonconductive, thus resetting the counting circuit so that when the pulses from the circuits 13 and 14 subsequently regain coincidence, valve device Tl will be rendered conductive and the counting operation will begin anew. When the valve device T1 is rendered nonconductive, the voltage at junction 74 rises. This applies a reset pulse to valve devices T12 and T18 rendering them conductive so as to condition valve devices T1 and T17 for the succeeding pulse. The reset pulse is also applied to cathode T19c rendering the auxiliary gate nonconductive until the next coincident pulses. This insures not closing the circuit breaker until a predetermined number of consecutive cycles of the source frequencies are substantially in phase, thus indicating substantial synchronization.

From the above description and the accompanying drawing, it will be apparent that I have provided in a simple and etfective manner for controlling the operation of a circuit breaker to automatically connect different alternating-current circuits. Operation of the circuit breaker is limited to a condition where a predetermined number of consecutive cycles of the sources remain substantially in phase, and reset is effected whenever such condition does not attain, so as to condition the apparatus for a subsequent attempt at synchronization.

The sensitivity of the synchronizer may be readily changed for any one operating frequency by varying the widths of the pulses to permit greater or less latitude in overlap, merely by changing the differentiating circuits to provide ones with the desired resistor-capacitor relations. Likewise the differentiating circuits may be changed to provide the desired sensitivity at different operating frequencies over a wide range, merely by removing the plug-in type circuits and replacing them with others having the desired RC relations.

Since certain changes may be made in the abovedescribed construction, and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all the matter contained in the above description and shown in the accompanying drawing shall be considered as illustrative and not in a limiting sense.

I claim as my invention:

1. In synchronizing apparatus, a circuit breaker for connecting a pair of alternating-current circuits, means for producing impulses in response to substantial synchronism of said circuits, a counting circuit for effecting operation of the circuit breaker in response to a predetermined number of such impulses, and reset means producing impulses in predetermined phase relation with one of the circuits for resetting the counting circuit to restart counting said predetermined number of impulses in the event that the predetermined number of instances of coincidence in the circuits do not occur on consecutive cycles.

2. In combination, a circuit breaker for connecting two alternating-current circuits, counting means operable in response to a predetermined number of impulses to effect operation of the circuit breaker, a gate circuit for applying impulses to the counting means, circuit means connecting the gate circuit to said alternatingcurrent circuits for producing impulses only upon substantial coincidence in phase of said circuits, and reset means for producing impulses in predetermined phase shift relation with one of the circuits, said reset means including a pulse divider responsive to said impulses for applying reset impulses to the counting means in alternate relation.

3. The combination with a circuit breaker for connecting two alternating-current circuits, of a counting circuit for effecting operation of the breaker to connect the circuits in response to a predetermined number of pulses in sequence, valve means for applying pulses to the counting circuit, means including a clipping circuit for applying impulses to the valve means from each of the alternating-current circuits in accordance with the frequency thereof to produce a pulse each time said impulses are coincident, and means for applying reset impulses to the counting circuit sequentially for terminating a counting operation in the event of non-coincidence of said impulses.

4. In a synchronizing circuit for a circuit breaker operable to connect a pair of separate alternating-current sources, means including a counting circuit for closing the circuit breaker in response to a predetermined number of consecutive impulses, a gate circuit for applying impulses to the counting circuit, means including a clipping circuit and a differentiating circuit for applying pulses of electrical energy to the gate circuit in accordance with the frequencies of the sources so as to produce impulses only when the pulses are coincident, reset means for applying a reset pulse to the counting circuit when the breaker closes, and means including a reset gate circuit operating under the control of the aforesaid gate circuit for resetting the counting circuit whenever the pulses fail to coincide.

S. An electronic synchronizer for a circuit breaker operable to connect two sources comprising, a relay for effecting closing of the breaker, a counting circuit operable in response to a predetermined number of pulses of electrical energy to eifect operation of said relay, means including an electric valve device having a control electrode for applying pulses of electrical energy to the counting circuit in response to coincidence in phase angle of the sources, and means for resetting the counting circuit each time the sources fail to coincide as to phase angle.

6. In synchronizing apparatus, a counting circuit responsive to a predetermined number of pulses of electrical energy, a gate circuit for applying pulses to the counting circuit, circuit means connecting the gate circuit to a pair of alternating-current circuits which are to be connected for applying voltage pips therefrom to the gate circuit for rendering it conductive when the circuits are in synchronism, a reset circuit for resetting the counting circuit when the gate circuit fails to apply a pulse to the counter circuit on any successive cycle of the alternating current, and means including an auxiliary gate circuit and a phase shift circuit for selectively applying reset impulses to the counting circuit to render portions thereof nonconductive.

7. Synchronizing apparatus for a circuit breaker disposed to connect a pair of alternating-current circuits comprising, a counting circuit including a plurality of grid controlled valve devices arranged to conduct sequentially in response to consecutive pulses of electrical energy, a gate circuit including a valve device for applying pulses of electrical energy to the counting circuit, circuits including clipping and differentiating circuits for applying control impulses to the gate circuit valve device from the alternating-current circuits for rendering it operative when the control impulses are in phase, reset means including a pulse divider for selectively applying blocking voltages to different ones of the counting circuit valve devices to render them nonconductive.

8. The combination with a circuit breaker operable toconnect a pair of alternating-current circuits connected to different sources, of a counter including a plurality of electric valves connected to be rendered conductive in succession in response to successive pulses of electrical energy, a relay controlled by the counter for effecting operation of the circuit breaker in response to a predetermined number of pulses, switch means operable in response to closing of the breaker for deenergizing said relay, circuit means including clipping and differentiating means for each of the pair of circuits for producing voltage pulses in response to successive cycles of the source frequency of each of the circuits, a gate circuit for applying a pulse to the valves of the counter each time the pulses from the circuits are in phase, a reset circuit for applying blocking pulses to the valves, and circuit meansincluding an auxiliary gate circuit controlled by pulses from the aforesaid gate circuit and a phase shaft circuit for applying control pulses to the reset circuit for resetting the counter circuit if fewer than the predetermined number of impulses from the aforesaid gate circuit occur on consecutive cycles of the I sources.

9. In a synchronizing circuit for a circuit breaker arranged to connect two alternating-current circuits, a

counting circuit including a plurality of electric valve devices connected in cascade relation for sequentially responding to consecutive pulses of electrical energ each of said devices being arranged to apply a positive bias to the succeeding device for rendering it conductive in response to the next pulse, a relay operable in response to conductivity of the last of said devices for closing the breaker, a switch actuated by the breaker for rendering said last device nonconductive, a main gate valve device having a cathode connection for applying pulses to the valve devices of the counting circuit, a blocking circuit for applying a blocking pulse from each valve device of the counting circuit to render the previous valve device noncontluctive, circuit means including clipping and dif ferentiating circuits for applying pulses from each of the circuits to the main gate valve to render said valve conductive only when such pulses are in phase, a pulse divider circuit for selectively applying blocking pulses to the odd and even numbered valves of the counting circuit to render them nonconductive, and means including an auxiliary gate valve device and a phase shift circuit for applying pulses to the divider circuits from one of the two alternating-current circuits.

l0. Synchronizing apparatus comprising, a counting circuit for effecting operation of a breaker to connect two alternating current circuits in response to a predetermined number of pulses, a coincident gate circuit for applying pulses to the counting circuit, means for applying pulses to the gate circuit from both of the alternating current circuits, and means for applying a reset pulse to the counting circuit to start it counting a new sequence of pulses in the event that the predetermined number are not successive.

ll. Synchronizing apparatus comprising, a control relay for effecting operation of a circuit breaker to connect two alternating current sources, a counting circuit for affecting operation of the control relay in response to a predetermined number of pulses, means producing pulses in accordance with successive cycles of each of the sources, a gate circuit for applying pulses to the counting circuit in response to coincidence between successive pulses from said sources, and means for applying a reset pulse to the counting circuit each cycle from one of the sources to terminate a counting operation and commence a new one in the event of failure of the gate circuit to apply a predetermined number of successive pulses.

References Cited in the file of this patent UNITED STATES PATENTS 2,231,713 Gulliksen Feb. 11, 1941 

